content: /* Copyright (C) 2016-2018 Alibaba Group Holding Limited
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  ==============================================================================*/
  
  // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package com.google.protobuf;
  
  /**
   * Provide text format escaping support for proto2 instances.
   */
  final class TextFormatEscaper {
    private TextFormatEscaper() {}
  
    private interface ByteSequence {
      int size();
      byte byteAt(int offset);
    }
  
    /**
     * Escapes bytes in the format used in protocol buffer text format, which
     * is the same as the format used for C string literals.  All bytes
     * that are not printable 7-bit ASCII characters are escaped, as well as
     * backslash, single-quote, and double-quote characters.  Characters for
     * which no defined short-hand escape sequence is defined will be escaped
     * using 3-digit octal sequences.
     */
    static String escapeBytes(final ByteSequence input) {
      final StringBuilder builder = new StringBuilder(input.size());
      for (int i = 0; i < input.size(); i++) {
        final byte b = input.byteAt(i);
        switch (b) {
          // Java does not recognize \a or \v, apparently.
          case 0x07: builder.append("\\a"); break;
          case '\b': builder.append("\\b"); break;
          case '\f': builder.append("\\f"); break;
          case '\n': builder.append("\\n"); break;
          case '\r': builder.append("\\r"); break;
          case '\t': builder.append("\\t"); break;
          case 0x0b: builder.append("\\v"); break;
          case '\\': builder.append("\\\\"); break;
          case '\'': builder.append("\\\'"); break;
          case '"' : builder.append("\\\""); break;
          default:
            // Only ASCII characters between 0x20 (space) and 0x7e (tilde) are
            // printable.  Other byte values must be escaped.
            if (b >= 0x20 && b <= 0x7e) {
              builder.append((char) b);
            } else {
              builder.append('\\');
              builder.append((char) ('0' + ((b >>> 6) & 3)));
              builder.append((char) ('0' + ((b >>> 3) & 7)));
              builder.append((char) ('0' + (b & 7)));
            }
            break;
        }
      }
      return builder.toString();
    }
  
    /**
     * Escapes bytes in the format used in protocol buffer text format, which
     * is the same as the format used for C string literals.  All bytes
     * that are not printable 7-bit ASCII characters are escaped, as well as
     * backslash, single-quote, and double-quote characters.  Characters for
     * which no defined short-hand escape sequence is defined will be escaped
     * using 3-digit octal sequences.
     */
    static String escapeBytes(final ByteString input) {
      return escapeBytes(new ByteSequence() {
        @Override
        public int size() {
          return input.size();
        }
        @Override
        public byte byteAt(int offset) {
          return input.byteAt(offset);
        }
      });
    }
  
    /**
     * Like {@link #escapeBytes(ByteString)}, but used for byte array.
     */
    static String escapeBytes(final byte[] input) {
      return escapeBytes(new ByteSequence() {
        @Override
        public int size() {
          return input.length;
        }
        @Override
        public byte byteAt(int offset) {
          return input[offset];
        }
      });
    }
  
    /**
     * Like {@link #escapeBytes(ByteString)}, but escapes a text string.
     * Non-ASCII characters are first encoded as UTF-8, then each byte is escaped
     * individually as a 3-digit octal escape.  Yes, it's weird.
     */
    static String escapeText(final String input) {
      return escapeBytes(ByteString.copyFromUtf8(input));
    }
  
    /**
     * Escape double quotes and backslashes in a String for unicode output of a message.
     */
    static String escapeDoubleQuotesAndBackslashes(final String input) {
      return input.replace("\\", "\\\\").replace("\"", "\\\"");
    }
  }
  